109 lines
4.5 KiB
Python
109 lines
4.5 KiB
Python
from typing import Dict, Optional, List, Callable
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from dataclasses import Field, asdict
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import sqlite3 as sql
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from commons import _convert_sql_format, _convert_type
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def _get_default(default_object: object, type_overload: Dict[Optional[type], str]) -> str:
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"""
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Check if the field's default object is filled,
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if filled return the string to be put in the,
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database.
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:param default_object: The default field of the field.
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:param type_overload: Type overload table.
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:return: The string to be put on the table statement,
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empty string if no string is necessary.
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"""
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if type(default_object) in type_overload:
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return f' DEFAULT {_convert_sql_format(default_object)}'
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return ""
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def _create_table(class_: type, cursor: sql.Cursor, type_overload: Dict[Optional[type], str]) -> None:
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"""
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Create the table for a specific dataclass given
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:param class_: A dataclass.
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:param cursor: Current cursor instance.
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:param type_overload: Overload the Python -> SQLDatatype table
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with a custom table, this is that custom table.
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:return: None.
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"""
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fields: List[Field] = [class_.__dataclass_fields__[key] for
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key in class_.__dataclass_fields__.keys()]
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fields.sort(key=lambda field: field.name) # Since dictionaries *may* be unsorted.
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sql_fields = ', '.join(f"{field.name} {_convert_type(field.type, type_overload)}"
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f"{_get_default(field.default, type_overload)}" for field in fields)
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sql_fields = "obj_id INTEGER PRIMARY KEY AUTOINCREMENT, " + sql_fields
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cursor.execute(f"CREATE TABLE IF NOT EXISTS {class_.__name__.lower()} ({sql_fields});")
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def _create_entry(self) -> None:
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"""
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Given an object, create the entry for the object. As a side-effect,
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this will set the object_id attribute of the object to the unique
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id of the entry.
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:param self: Instance of the object.
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:return: None.
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"""
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with sql.connect(getattr(self, "db_path")) as con:
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cur: sql.Cursor = con.cursor()
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table_name: str = self.__class__.__name__.lower()
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kv_pairs = [item for item in asdict(self).items()]
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kv_pairs.sort(key=lambda item: item[0]) # Sort by the name of the fields.
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cur.execute(f"INSERT INTO {table_name}("
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f"{', '.join(item[0] for item in kv_pairs)})"
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f" VALUES ({', '.join(_convert_sql_format(item[1]) for item in kv_pairs)});")
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self.__setattr__("obj_id", cur.lastrowid)
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con.commit()
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def _update_entry(self) -> None:
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"""
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Given an object, update the objects entry in the bound database.
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:param self: The object.
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:return: None.
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"""
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with sql.connect(getattr(self, "db_path")) as con:
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cur: sql.Cursor = con.cursor()
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table_name: str = self.__class__.__name__.lower()
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kv_pairs = [item for item in asdict(self).items()]
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kv_pairs.sort(key=lambda item: item[0])
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query = f"UPDATE {table_name} " + \
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f"SET {', '.join(item[0] + ' = ' + _convert_sql_format(item[1]) for item in kv_pairs)}" + \
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f"WHERE obj_id = {getattr(self, 'obj_id')};"
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cur.execute(query)
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con.commit()
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def remove_from(class_: type, obj_id: int):
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with sql.connect(getattr(class_, "db_path")) as con:
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cur: sql.Cursor = con.cursor()
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cur.execute(f"DELETE FROM {class_.__name__.lower()} WHERE obj_id = {obj_id}")
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con.commit()
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def _remove_entry(self) -> None:
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"""
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Remove the object's record in the underlying database.
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:param self: self instance.
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:return: None.
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"""
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remove_from(self.__class__, getattr(self, 'obj_id'))
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def datalite(db_path: str, type_overload: Optional[Dict[Optional[type], str]] = None,
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*args, **kwargs) -> Callable:
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def decorator(dataclass_: type, *args_i, **kwargs_i):
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type_table: Dict[Optional[type], str] = {None: "NULL", int: "INTEGER", float: "REAL",
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str: "TEXT", bytes: "BLOB"}
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if type_overload is not None:
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type_table.update(type_overload)
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with sql.connect(db_path) as con:
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cur: sql.Cursor = con.cursor()
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_create_table(dataclass_, cur, type_table)
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setattr(dataclass_, 'db_path', db_path) # We add the path of the database to class itself.
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dataclass_.create_entry = _create_entry
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dataclass_.remove_entry = _remove_entry
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dataclass_.update_entry = _update_entry
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return dataclass_
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return decorator
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